Catalysis is a science at the interface between chemistry, physics, biology, engineering and material sciences that enables chemical processes to be realized in a cost-, energy and eco-efficient way. More than 80% of the processes in the chemical industry, worth approcimately Eur 1500 billion, depend on cataytic technologies. Catalysis gives a key contribution to sustainable mobility, quality of life and health protection and environment protection, as well as the rational use of resources. The present talk will discribe the essentials of catalysis in high-efficiency conversion of energy, and followed by an introduction of the character and application of the catalysts in several very important processes of energy conversion. The emphasis is on the optimal utilizations of natural gas (methane) and the controlled conversion of syngas to the alternative energy, such as liquid fuel and alcohols. In the present talk, the nano-effects as the unique properties in catalysis will be demonstrated, and some important concepts, such as the so-called size- dependency, quantum well states and synergetic confinement, will be illustrated through the real processes catalyzed by nano particles, porous materials and carbon nanotubes.